Process and apparatus for making helical tension springs having particularly great preliminary tension



v e 8N h 4 S v H 1 2 e July 8, 1941. O SCHMID PROCESS AND APPARATUS FOR MAKING HELICAL T PARTICULARLY GREAT PRELIMINARY TENSION Filed Sept 15, 1939 I-m/ewfor:

Otto chmid 12.,

y 1941- o. SCHMID 2.248.440 PROCESS AND APPARATUS FOR MAKING HELICAL TENSION SPRINGS HAVING PARTICULARLY GREAT PRELIMINARY TENSION Filed Sept. 15, 1939 2 Sheets-Sheet 2 Ivn/n Zor: Otto d'clzmdci Patented July 8, 1941 PROCESS AItTD APPARATUS FOR MAKING HELICAL TENSION SPRINGS HAVING PAR- TICULARLY GREAT PRELIIVIINARY TEN- SION om Schmid, Reutlingen, Germany Application September 15, 1939, Serial No. 295,128 In Germany August 7, 1937 14 Claims.

This invention relates to a process and an apparatus for the production of helical tension or draw springs of high initial tension.

Machines are known in which initial tension is obtained by having the winding tools movable or rotatable with respect to each other in a direction parallel to the axis of the spring, so that'the Wire is given a certain deflection out of the winding plane. It is an object of the present invention to achieve a higher amount of pretensioning than has been attained in such prior machines. Another object is to provide a device which will wind highly pretensioned springs which can be cut to any desired length during formation.

According to the invention each spring is wound in two stages, consisting of a preliminary winding stage and a finishing winding stage following immediately thereafter the spring being wound to a larger diameter than desired in the first stage and to the desired final diameter in the second stage.

In order to be able to wind springs of different diameter, with the same apparatus the winding tools, or their points of engagement on the wire,

are made adjustable in the direction of the initial points of the bend of the fed wire. In this way, the winding effect of the winding tools remains the same with each adjustment.

Furthermore, in order to be able to adjust the amount of pretensioning or the pitch of the helical springs, the winding tools of the prewinding stage are adjustable in such manner that the angle between their winding plane and the winding plane of the winding tools of the finishing winding stage may be varied. To this end, they are carried on a common holder which is oscillatable about an axis which is located in the extension of the axis of the fed wire, whereby the winding plane of these tools can be adjusted more or ess obliquely to the axis of the spring. The winding tools of the finishing winding stage are carried on a common sliding carriage which is movable parallel to the axis of the spiral springs to be made, and preferably carry the device for cutting 01f the springs.

With the device according to the invention, it is not necessary to twist the winding tools unnaturally in order to bend the wire out of the winding plane. On the contrary, the winding tools can be easily adjusted, with their wire conveying rollers, in the direction of the helical lines of the spring winding, whereby a long holding duration of the winding tools is ensured.

' The device forparrying out the process according to the invention is shown by way of example in the accompanying drawings, in which Figure 1 is a front view of the complete spring winding apparatus,

Figure 2 is a side view of the prewinding stage viewed from the left,

ing stage.

Figure 3 is a side view of the finishing winding stage seen from the right, and

Figure '4 illustrates the'process and shows the adjustment of the winding tools for dilferent diameters of springs.

The wire a to be wound or coiled is fed in the direction of the arrow by'the two conveyor cylinders b and is delivered by a guide 0 to the winding tools dand e. The two winding tools d, d constitute the prewinding stage and the three winding tools e,'e, e constitute the finishing wind- The two tools d, d bend the wire a from a point A into an arc ABC, the radius of which, as shown by Figures 1 and 4, is greater than the radius of the finished spring I. Following thereon, the three winding tools e, e, e bend the wire a to the final desired spring size DEF.

So that springs f of different diameters may be wound by means of the same apparatus, the winding tools d, d and e, e, e are forwardly and backwardly movable so that their working points B, G, D, E and F on the wire a move in the direction of the initial point A of the bending of the wire a, as shown by arrows in Figures 1 and 4.

The winding tool d, d and e, e, e are carried on slides g and h which can be shifted longitudinally and fixed, and the direction of movement of which is parallel to the path of movement (indicated by arrows) of the working points B, C, D. E, F. The slides .11 are located in guides i fitted on a common holder is. The holder is is oscillatable about two pivots l which are carried in two bearing blocks fitted on the machine frame m, and can be fixed in any adjusted position by means of two set screws 11, so that the amount of pretensioning or the pitch of the spring i may be varied. The two pivots l, are located in the extension of the axis of the supplied wire a. The more the holder is is oscillated, with its prewinding tools d, d, the greater will be the pitch of the wire arc section A, B, C.

The slides 12. of the finishing winding tools are longitudinally movable and are adapted to be fixed in guides o of a common carriage p. The latter, for the purpose of varying pretensioning or the pitch of thescrews f is movable on the machine frame m parallel to the axis of the spring by means of a thumb screw q Fig. 3. If the pretensioning is to be increased, the carriage p is drawn backwards, so that a greater deflection of the wire a takes place and vice versa.

With the process and the apparatus according to the inventiomsprings of any desired length can be produced. In order to be able to make springs of an exactly definite number of turns, a cutting-off device is provided, which consists of a movable cutter s and a fixed counter knife r. The counter knife 1' is introduced into the finished spring ,1 and the cutter s moved towards it, whereby a section of the finished spring 1 is cut and a set of winding tools arranged to operate on the wire curved by the first mentioned set to impart further curvature to the wire to bring it to final diameter and form.

2. A device for making helical tension springs with high initial tension, comprising means for feeding spring wire to an initial bending point, a set of winding tools adapted to impart preliminary curvature to said wire of larger diameter than that of the helical spring to be made therefrom, a set of winding tools arranged to operate on the preliminary curved wire to increase the curvature thereof to bring said wire to final diameter and form, and means for adjusting said winding tools along lines which intersect at said initial bending point.

3. A device for making helical tension springs with high initial tension, comprising a set of winding tools adapted to impart to spring Wire preliminary curvature of larger diameter than that of the helical spring to be made therefrom, a set of Winding tools arranged to operate on the wire curved by the first mentioned set to impart further curvature to the wire to bring it to final diameter and form, a carriage supporting the second-mentioned set of winding tools, a pivot for said carriage, said pivot being coaxial with the helical spring being formed, and means for adjusting the angular position of the carriage about said pivot.

4. A device for making helical tension springs with high initial tension, comprising a set of winding tools adapted to impart to spring wire preliminary curvature of larger diameter than that of the helical spring to be made therefrom, a set of winding tools arranged to operate on the wire curved by the first mentioned set to impart further curvature to the wire to bring it to final diameter and form, a carriage supporting the final winding tools, and means for adjusting said carriage in a direction parallel to the axis of the helical spring being formed.

5. A device for making helical tension springs with high initial tension, comprising a set of winding tools adapted to impart to spring wire preliminary curvature of larger diameter than that of the helical spring to be made therefrom,

a set of winding tools arranged to operate on the wire curved by the first mentioned set to impart further curvature to the wire to bring it to final diameter and form, a carriage supportingthe preliminary winding tools, a pivot for said carriage said pivot being co-axial with the helical spring being made, means for adjusting the angular position of the carriage about said pivot, a carriage supporting the final winding tools, and means for adjusting said last mentioned carriage in a direction parallel to the axis of the helical spring being formed.

6. A method for making helical tension springs in which the wire of the spring is wound in a helix in two successive stages, comprising winding the wire as a preliminary stage into a coil of larger diameter than that finally required, and then winding the thus treated wire directly from the larger diameter into a final and smaller diameter and helical form as the second stage.

'7. A method of producing helical tension springs from wire comprising winding the wire into a preliminary curved configuration of a larger diameter than that required for the finished spring, and further winding the curved wire directly from the larger diameter into the final curved configuration having a smaller diameter equal to the desired spring.

8. A device according to claim 1, in which the preliminary winding tools are adjustable in a direction parallel to the axis of the helix to vary the angle between the winding plane of said tools and the winding plane of the tools of the final winding.

9. Device according to claim 4 wherein means for cutting the spring wire are carried on said carriage.

10. Device according to claim 5 wherein means for cutting the spring wire are provided on the carriage of the final winding tools.

11. A machine for making helical tension springs with high initial tension, comprising a holder, a set of winding tools mounted on said holder and adapted to impart to spring wire preliminary curvature of larger diameter than that of the finished helical spring, a carriage, and a set of winding tools arranged on said carriage to operate on the wire curved by the first mentioned set to impart further curvature to the wire to bring it to the final diameter and form of the finished spring.

12. A machine according to claim 11, in which each winding tool is provided with an adjustable mounting so that each tool may be adjusted relative to its holder or carriage.

13. A machine according to claim 11, in which the holder is provided with adjustable and pivotal mounting means and in which the carriage is provided with adjustable and pivotal mounting means, the pivotal mounting means for the holder beingrco-axial with the direction of feed of the wire into the machine and the pivotal mounting means for the carriage being co-axial with the helical spring being formed.

14. A machine for making helical tension springs with high initial tension, comprising means for feeding a spring wire into the machine at a tangent to the helical spring to be wound, a holder, at set of winding tools mounted on said holder and adapted to impart to spring Wire preliminary curvature of larger diameter than that of the finished helical spring, a carriage, a set of winding tools arranged on said carriage to operate on the wire curved by the first mentioned set to impart further curvature to the wire to bring it to the final diameter and form of the finished spring, and cutting means on the carriage to cut the wire feeding into the machine by the feeding means after the spring has been completed.

OTTO SCHMID. 

